The instant application should be granted the priority dates of Jan. 3, 2006, the filing date of the corresponding German patent application 10 2006 000 810.3 as well as Dec. 29, 2006 the filing date of the International patent application PCT/EP2006/012591.
The invention relates to an interconnected arrangement of a plurality of modules comprising at least one, but preferably a plurality, of light-emitting diode chips connected in series or in parallel. Such individual modules are, for example, known from the product data sheet “High Performance Square—built-in PCB lighting modules” of Vossloh-Schwabe Deutschland GmbH of 04/2005.
With individual modules as light sources operating on the basis of light-emitting diode chips there is the problem that the respective forward voltage range of the light-emitting diode chips used is dictated by the manufacturing process. The use of light-emitting diode chips with narrow forward voltage ranges may be implemented on an individual module or a plurality of individual modules. With mass production, however, the use of light-emitting diode chips selected only with a narrow, restricted forward voltage range is very uneconomical with regard to a plurality of manufactured modules.
Appropriately, therefore, forward voltage selected light-emitting diodes interconnected in parallel are only provided in switching systems located on individual modules. Such individual modules are stable per se. However, if a plurality of individual modules are connected in parallel in module arrangements interconnected to one another, individual current sources are respectively connected in series with the modules which are interconnected individually in parallel or in parallel series. These current sources stabilize the operation of the individual modules.
Such a connection in series of current sources and an associated LED module may be easily interconnected to module systems supplied by a supply voltage, with individual modules connected in parallel As the operating stability of an individual LED module is highly dependent on a low operating temperature, the respective current sources connected in series to the individual modules are generally arranged separately.
To this end, clocked current sources with high efficiency relative to the input voltage are used as well as linear operating current sources, for example in the form of transistor circuits which operate as “variable series resistors”. With these linear current sources, however, the efficiency and thus the inherent heat dissipation is dependent on the delta of the input voltage to the control output voltage. A linear current source may, therefore, only be operated with high efficiency, i.e. low heat dissipation, when the input voltage is not much greater than the control output voltage.
Insofar as clocked current sources are independent of a defined input voltage, as might be necessary with linear systems, generally with known LED module systems connected in parallel, clocked current sources are exclusively used. The drawback associated with these clocked current sources, however, is that such current sources are substantially more complicated and thus more expensive than linear current sources.
An interconnected arrangement of light-emitting diode chips is already known from DE 103 18 780 A1, which are supplied by constant current circuits, the voltage source being set for the purpose of minimizing the heat dissipation in the linear controllers. However, it is therefore necessary to measure the voltage on all light-emitting diode chip arrangements and/or on all current sources.
The object of the invention, therefore, is to demonstrate a possibility of interconnecting in parallel individual modules comprising in particular a plurality of light-emitting diode chips, in which despite variable forward voltages on the modules to be interconnected to one another, linear current sources and/or linear constant current circuits may be used in a simple circuit construction.